Multipactor Dynamics in High-Power Microwave Systems

The multipactor effect arises when electrons within a high-power microwave device resonate between metallic or dielectric surfaces, driven by alternating electromagnetic fields, and generate successive avalanches of secondary electrons. This phenomenon can limit power-handling capability, degrade signal integrity and provoke localized heating or breakdown in satellite communication links, radar systems and plasma-heating antennas. Dynamics of multipactor depend critically on secondary electron emission properties of surface materials, the gap geometry and the spatial distribution of RF fields. Space-charge accumulation, surface charging of dielectrics and gas adsorption further modulate the onset and saturation of the discharge. Accurate prediction of the multipactor threshold and understanding of its evolution are essential for robust component design, qualification testing and on-orbit reliability. Contemporary approaches combine reduced electromagnetic models, Monte Carlo and particle-in-cell simulations with statistical sensitivity analyses to capture the interplay of surface characteristics, field non-uniformities and collisional processes. Mitigation strategies span material engineering to lower secondary electron yield, tailored surface coatings, application of external bias fields and novel device geometries such as groove gap waveguides. Advances in measurement uncertainty assessment and diagnostic techniques underpin both ground qualification and in-field monitoring of multipactor phenomena.

Research from Nature Portfolio

A recent statistical investigation has quantified how uncertainties in secondary electron yield parameters influence the predicted multipactor threshold. By employing polynomial chaos expansion and Sobol sensitivity indices, this work demonstrates that random variations in yield parameters can dominate threshold uncertainty, with distinct contributions from peak yield, energy at peak yield and emission curve shape. These insights offer a rigorous framework for incorporating material-surface variability into design margins, improving predictive confidence for high-power microwave components.

Multipactor Dynamics in High-Power Microwave Systems publication trend

The graph below shows the total number of articles in multipactor dynamics in high-power microwave systems across all publications each year (not limited to Nature Index journals).

Technical terms

Multipactor: A resonant vacuum discharge in which electrons oscillate under RF fields between surfaces, causing exponential secondary‐electron growth.

Secondary Electron Yield (SEY): The ratio of emitted secondary electrons to incident primary electrons on a surface, critical for assessing multipactor susceptibility.

Multipactor Threshold: The minimum RF field amplitude or power level at which a self‐sustained multipactor discharge initiates.

Space‐Charge Effect: The influence of accumulated electron charge on local electric fields, which alters electron trajectories and discharge evolution.

References

1. Uncertainty Budget in Microwave High-Power Testing. IEEE Transactions on Instrumentation and Measurement (2023).
2. Recent advances in multipactor physics and mitigation. High Voltage (2023).
3. Theoretical and Experimental Results for Multipactor Effect in Groove Gap Waveguide Bandpass Filters With Inductive Coupling Irises. IEEE Access (2024).
4. Analysis of multipacting threshold sensitivity to the random distributions of the secondary electron yield parameters. Scientific Reports (2024).